If confirmed, Nielsen, who is currently Trump’s deputy chief of staff, will lead the agency charged with protecting America’s borders, guarding against cybersecurity threats and spearheading disaster relief efforts.

Nielsen is a cybersecurity expert and former Homeland Security official who is widely cheered in Republican circles for her experience. However, Democrats have sounded alarm about her lack of leadership experience, citing the challenge of managing a sprawling agency with roughly 240,000 employees.

The department has been without a Senate-confirmed leader since the end of July, when John KellyJohn Francis KellyMORE moved to the White House to serve as Trump’s chief of staff. Nielsen, who at the time was serving under Kelly at DHS, moved with him to the White House.

“Our nation is facing constantly-evolving threats, making it all the more important for strong, permanent leadership at DHS. Ms. Nielsen’s prior experience at the department, background in cybersecurity, and tenure with General Kelly will serve her well in this challenging position,” Johnson said in a statement Tuesday evening. “I hope the Senate will take up Ms. Nielsen’s nomination as quickly as possible.”

Elaine Duke has served as acting secretary of Homeland Security since Kelly moved to the White House.